The present invention relates to the production of carbon black by means of an incomplete air-acetylene combustion reaction.
Carbon black has many industrial applications on account of its lubricating and heat insulating properties. It is thus applied in particular in metallurgy as a luting agent for moulds, ingot moulds, chill-casting moulds or the like, into which a molten metal is cast.
The carbon black produced by the apparatus known at present, which utilise incomplete combustion of acetylene in air, is of poor quality however, which is deleterious to particular industrial applications which are already known, and prevents the extension of its application to other industries.
For example, the granulometry of this carbon black which is a function of the air/C.sub.2 H.sub.2 ratio, is thus difficult to control has a fatty consistency and the deposits formed on the metallurgical moulds have an uneven thickness, which implies an inconsistency in its lubricating capacity and in its heat insulating properties.
Furthermore, this carbon black obtained with known apparatus, contains aromatic hydrocarbons, such as benzene and naphtalene, which stick to the walls of the moulds or the like, and jeopardise their subsequent cleaning. These aromatic carbides act as bonders for the granules and endow the carbon black with a flocculent consistency.
Finally, the operation of such known apparatus is often disturbed by the deposits of tars on the air and acetylene feed pipes.
It is thus an object of the invention to minimise or eliminate the disadvantages hereinbefore referred to and to this end proposes a device which comprises heating means organised to cause heat cracking of the acetylene molecules prior to the aforesaid combustion reaction.